From Wikipedia: "NGC 3198, also known as Herschel 146 is a
barred spiral galaxy in the
constellationUrsa Major. It was discovered by
William Parsons, 3rd Earl of Rosse (Lord Rosse), sometime before 1850. NGC 3198 is located in the
Leo Spur, which is part of the
Virgo Supercluster, and is approximately 47 million light years away." This galaxy has been studied as part of rotation curve and dark matter studies. From a Caltech paper (
https://ned.ipac.caltech.edu/level5/March01/Battaner/node3.html): "The interpretation of rotation curves of spiral galaxies as evidence of DM halos was probably first proposed by
Freeman (1970) who noticed that the expected Keplerian decline was not present in
NGC 300 and
M33, and considered an undetected mass, with a different distribution for the visible mass. The observation of flat rotation curves was later confirmed and the DM hypothesis reinforced by successive studies.
Rubin, Ford and Thonnard (1980) and Bosma (
1978,
1981a,
b) carried out an extensive study, after which the existence of DM in spiral galaxies was widely accepted.
Van Albada et al. (1985) analyzed the rotation of
NGC 3198 and the distribution of its hypothetical DM, concluding that this galaxy has a dark halo, in agreement with the paper by Ostriker and Peebles (1987) about the stability of disks. The rotation of spirals was soon considered the most solid proof for the existence of DM in the Universe, particularly important when it was later believed that
= 1. Other decisive papers were produced by
Begeman (1987) and
Broeils (1992)."
Data acquisition: Barry Wilson & Steve Milne
Processing: Barry Wilson
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